The present invention relates to an electrophotographic copying apparatus and more particularly, to an electrophotographic copying apparatus equipped with a copying coverage indication device which indicates the maximum area to be covered by copying, i.e. the area vailable for copying or copying coverage, on an original platform of the electrophotographic copying apparatus capable of selectively using copy paper sheets of a plurality of different sizes and provided with a variable magnification function.
Generally, in electrophotographic copying apparatuses, it is so arranged that an original to be copied placed on a transparent platform is illuminated by a light source or exposure lamp from the under surface of the original so as to project the light-wise image reflected from the original onto a photosensitive member or photoreceptor through an optical system including a lens assembly, etc., and in the case of copying at a magnification of 1:1 or equal size magnification, since the area to be covered by copying with respect to the size of the selected copy paper sheets is the size of the copy paper sheet itself, an operator of the copying apparatus has only to align one edge of the original with a reference side or datum line given on the original platform to set the original within a range indicated by a size scale or the like provided along the reference side.
However, in an electrophotographic copying apparatus capable of selectively using copy paper sheets of a plurality of different sizes and also provided with a variable magnification function, the size of the copy paper sheet does not necessarily coincide with the area to be covered by the copying operation or the area available for copying, and it has been quite troublesome for the operator to select a copy paper sheet of optimum size based on the size of the original and the magnification for the copying or to judge the size of the original which can be used according to the selected copy paper sheet size and the copying magnification, thus frequently giving rise to such inconveniences as employing copy paper sheets of unnecessarily large size, or undesirably using copy paper sheets too small for the size of the copied images.
In the conventional copying apparatuses of this kind, determination of the copy paper sheet size or the area to be covered by copying has almost been left to the operator, and although some of the conventional copying apparatuses are arranged merely to indicate the maximum area to be covered by copying for each copying magnification by scales and the like, there has been no arrangement for indicating the area available for copying in relation with the copy paper sheet size, thus still imposing troubles as described above on the operators.
Meanwhile, no particular attention has yet been drawn to automatically effecting determinations as described above, since in such an automated arrangement, if many kinds of copy sheets are involved, with a variety of copying magnifications, extremely expensive and complicated mechanisms are inevitably required, and thus, the inconveniences on the part of the operators as described earlier have not at all been eliminated at the present stage.